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3.1.1 Hardware Test
During power-up, the CMA 56 automatically carries out a hardware test; the
device only turns itself ON when this self-test is passed. A new attempt is
made every 8 seconds if a malfunction occurs.
3.1.2 Temperature Monitoring
Dependent on the load and the current output, the internal power dissipation
results in the heating up of the CMA 56.
When the temperature threshold is reached, the temperature monitoring
function automatically switches the device OFF. The LED display at the front
panel flashes red/dark (0.5s / 0.5s).
The time until the device is switched OFF due to overheating depends on the
following factors:
- the duty factor (ON/OFF time) of the output currents,
- the load,
- the ambient temperature, and
- the temperature within the device due to previous tests.
Typical data:
• At maximum load (3 x 50A
rms
):
ambient temperature = 25°C
internal device temperature = 25°C
outputs short circuited (max. power loss in CMA 56)
unit switches itself OFF after approx. 4 min.
• For a typical application:
Conditions as above and duty factor 1:2 (e.g. 5s ON / 10s OFF)
unit will never switch OFF.
After the unit switched itself OFF, the CMA 56 will "wait" until the temperature
in the device has dropped under a threshold. This threshold is about 5°C
below the switch-OFF threshold, i.e. the temperature monitoring function has a
hysteresis behavior.
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General